It is already known that self-propelled machines of different kinds are equipped with safety devices of the deadman's handle type, but when it comes to vibratory plates it is less usual. Because heavier plates have considerable propulsion power and are often used in small spaces or where stationary barriers could exist, it is very desirable that they be equipped with the above-mentioned safety device that works independently of whether the motion is forwards, or backwards, so that it can prevent accidents or other types of damage.